Bioprocess Optimization Of 1,3-Propanediol Production By Klebsiella Pneumoniae

Bioprocess optimization and feeding strategies for 1,3-propanediol (PDO) production by Klebsiella pneumoniae were investigated in this thesis, the results were reported as follows:1. The enviromental varibles like culture temperature, pH and aeration rate were optimized, their optimum values were 37℃,7.0 and 0.5vvm, repectively.2. The carbon sources including glycerol and glucose were utilized for PDO fermentation, the results showed that there was no signifiant differences in PDO yeild when industrial glycerol(90%content) or chemical grade glycerol(nearly 99%content) was used as the main carbon source. Meanwhile, it indicated that the optimum intial glycerol concentration was 40%for PDO production and cell growth. Also, glucose with low concentration (approximately 5.0 g/L) was benefit to improvement of PDO biosynthesis when it was added in the fermentation medium.3. The mixed alkalic solution containing NaOH, ammonmum, and KOH was applied to control pH during PDO fermention process. The findings showed that PDO yield using the mixed alkalic solution was 10.6 times than that of the control without pH control. Furthermore, a new glycerol feeding strategy was established, namely, the feed medium of glycerol with mixed alkalic soultion was automatically fed by coupling with pH control at 7.0 during the PDO fermentation process, resulting in that substrate glycerol concentration was kept at 20 g/L,the yield of PDO on glycerol was 0.5 g/g, molar yield of PDO on glycerol was 0.6 mol/mol, and PDO productivity was 2.2 g/(L·h). The highest PDO level of 53.5 g/L was obtained, which was 16%higher than that obtained with constant glycerol feeding strategy.